1. Field of the Invention
This invention relates to a structure for replacably mounting an operating member, such as glove, bag, filter, or the like in a wall port of a radiation shielding box.
2. Detailed Description of the Prior Art
In the case where a radioactive or other hazardous material must be indirectly handled or manipulated, such a material is placed in a shielded container, room or box and is handled by means of a glove, a bag, a filter, etc.
Heretofore, when it is required to handle or manipulate a shielded material in a shielding box, a transparent shielding box 1, as shown in FIG. 1, was employed. The outside of the box 1 is sealed. On the walls 2 of the box 1, there are provided gloves 3 into which the operator's hands can be put so that his hands can be inserted into the box 1. A bag of polyvinyl chloride 4 is for material to be inserted into or removed from the box, and a filter 5 for filtering polluted material is included in the shielding box. Such a shielding box as described above is well known in the art.
The box is provided with ports for securing the gloves and the bag. The construction of these ports will be described. As is shown in FIG. 2 and FIG. 3, a cylindrical fixed port 8 is fixedly inserted into an opening of the wall 2 through a ring-shaped packing 7 whose section is in the form of the letter "U". The base 9 of the glove 3 is placed over the outer wall of the fixed port and is tightly clamped with clamping parts, or an "O" ring 10 and a tightened sealing band 11.
With the shielding box thus constructed, an old glove is replaced by a new glove in accordance with the following method: First, the fingers of the new glove 12 are inserted into the old glove 3. Then, a sealing tool 18 consisting of disk-shaped steel plates 13 and 14, a cylindrical rubber section 15, and a screw member 17 with a handle 16 is inserted into the new glove 12. The rubber section 15 is inflated by operating the handle 15 as shown with the dotted line in FIG. 2, so that parts of the new and old gloves 12 and 3 are abutted against the inner wall of the fixed port 8 thereby to seal the box 1 from the outside. Then, the tightening band 11 is removed from the fixed port and the base 9 of the old glove 3 is folded about the "O" ring 10. In this operation, a slight amount of polluted material may be transferred to the surface of the base portion of the glove thus folded and to the outer wall of the fixed port 8. This polluted material must be completely removed from such parts.
Then, although not shown in the drawing, the base 19 of the new glove 12 is pulled over the base 9 of the old glove 3 folded and is placed on the periphery of the fixed port 8. Thereafter, the base 19 of the new glove thus placed is secured to the outer wall of the fixed port 8 with the tightening band 11. Then, the sealing tool 18 is released by operating the handle 16, and the old glove 3 is caught through the new glove 12 by the band so that the old glove 3 together with the "O" ring 10 is pulled into the box 1 and is allowed to drop therein. Finally, a new "O" ring is placed on the base 19 of the new glove. Thus the replacement of the old glove with the new glove has been completed.
In the case when an unnecessary material 20 is removed from the box 1, the material 20 is put in the bag as shown in FIG. 3, and a suitable part 21 of the bag 4 above the material 20 is sealed and then cut off to take the material 20 out of the box as shown in FIG. 4.
In contrast, if it is necessary to put a material 22 into the bag 4 from outside, a suitable part 25 of the bag is sealed as shown in FIG. 5. Then the material 22 is, put into the box 1 through the hole 24 of a port section 23, and the part 25 thus sealed is cut off inside the box 1.
As the removal or insertion of the material is frequently carried out, it will be required to replace the bag 4 with a new one. In this case, of course, the old bag 4 is removed from the port section 23. As is apparent from FIGS. 3 through 5, the conventional bag mounting structure is such that the bag is fixedly secured directly to the port section 23 with the tightening band 11 and the "O" ring 10. Accordingly, the replacement of the bag 4 is carried out by the use of the sealing tool 18, similarly as in the replacement of the glove 3.
Gloves 3 and the bags 4 are also provided at places on the wall of the box 1 in view of various internal conditions, where normally the glove or the bag is not used. However, these gloves and bags will be deteriorated with the lapse of time and must be replaced with new ones some time.
The filter 5 is not concretely illustrated; however, the replacement of the filter will become apparent from the following description: The filter 5 is inserted into a filter fixing frame provided on the wall 2 of the shielding box 1, and a retainer is placed over the filter thus inserted, at the outside of the shielding box 1. Thus, the provision of the filter 5 is completed. When the filter 5 should be replaced with a new one owing to the decrease of its filtering capacity or its pollution, the replacement of the filter is carried out by removing or opening the retainer.
However, in the above-described port sections of the glove and the filter, a part of the polluted material may leak out of the shielding box 1 during the replacement operation. Therefore, the conventional method is not completely safe. Furthermore, the conventional method is not economical because the replacement requires a special tool and the gloves are often wasted. In addition, it is rather troublesome to periodically inspect a number of gloves, which are not used so often, for damage or deterioration, which leads to the necessity of a great deal of labor.
Known in the art is an arrangement in which air supplying ducts (pipes) 27 for introducing clean air into the boxes 1 in order to clean the atmosphere in the boxes and exhaust ducts 28 for discharging the polluted air out of the boxes 1 are connected to the respective boxes 1, as shown in FIG. 6. In the midpoint of the exhaust duct 28, a filter case 30 including a filter 29 is connected through rubber tubes 31 and 32, so that the polluted air is discharged out of the box 1 through a stack 26. When the used filter is replaced with a new one, it is essential that the worker should not directly touch the polluted filter. Therefore, the replacement of the polluted filter 29 is carried as follows. First, the rubber tubes 31 and 32 are sealed to block the flow of air therein, and the duct mouths 33 and 34 of the polluted filter case 30 are removed from the respective rubber tubes 31 and 32 thereby to remove the filter case 30. Then, the duct mouths of a new filter case are respectively coupled to the ends of the ends of the sealed rubber tubes 31 and 33. Thus, the replacement of the polluted filter case has been completed.
In the case where a large volume of polluted air should be cleaned, it goes without saying that the use of only one filter case is insufficient, and a number of filter cases. as shown in FIG. 7, must be disposed horizontally or vertically. Accordingly, in the replacement of these number of filter cases, the worker must move back and forth or up and down. Furthermore, the replacement of the filter cases should be done within as short a period of time as possible in view of the worker's health. However, according to the conventional replacement method, it takes a lot of time to complete the replacement, and the polluted air might leak out.